This invention relates to new and useful improvements in compensating fuel measuring systems for engine fuel systems.
Many users or agencies associated with fuel consumption such as engine manufacturers, the automotive industry, the American Petroleum Institute, Governmental Agencies and the like, require an accurate determination of fuel consumption in units of weight or energy. Such accuracy is difficult to accomplish because of variations in the gravity and temperature of the fuel being tested or measured. For example, there can be at least 4 percent variation in the BTU per gallon of a given fuel due to variations in the API or specific gravity of the fuel alone. An additional 6 percent variation can occur due to variations in the temperature of the fuel being measured because fuel expands and contracts with changes in temperature.
The inaccuracy resulting from these conditions has induced the use of various types of compensating charts but such charts are inconvenient to use.
The inaccuracies mentioned have also induced users to meter by weight and thus use weight-type or mass-type meters instead of volumetric-type meters. While weight-type meters are accurate and are immune to variations in temperature and gravity, they have inherent disadvantages. One is that they are complex in construction, massive in relation to volumetric-type meters, and are expensive to manufacture. Another disadvantage is that they require a relatively large quantity of fuel thru-put before an accurate determination can be assured. Volumetric-type meters, on the other hand, are relatively simple and inexpensive to manufacture and give accurate metering almost instantaneously.